Where are all the aliens? Maybe they’re mostly microbial (and dead)

One of the enduring puzzles in astrobiology is why we haven’t found any alien life yet. Astronomers estimate there are between 200 and 400 billion stars in the Milky Way. The Kepler telescope has proven that many stars have planets, and if the Earth is in any way a typical planet, we should see some evidence of life elsewhere in the galaxy after 13.8 billion years. Except, of course, we don’t. This is known as the Fermi Paradox.

A new paper by astrobiologists Aditya Chopra and Charley Lineweaver of the Australian National University has a new explanation for why this might be so. It’s a modification of the so-called “Great Filter” theory, and it argues that life on most planets may become extinct not long after it first evolves.

The Great HEPA Filter

The “Great Filter” theory explains the Fermi Paradox by positing the existence of a specific bottleneck that prevents most species (or life in general) from reaching the point where the colonization of space is possible. Life might evolve frequently, but supernovae and gamma ray bursts sterilized many of the planets on which it evolved earlier in our galactic history. Maybe highly intelligent life has a tendency to over-consume the resources of its home planet, and therefore becomes extinct before developing the technology to colonize a galaxy. Life might be abundant, but the evolution of high intelligence and efficient tool use could be extremely rare.

What Chopra and Lineweaver propose is that life may evolve often, but only rarely survives long enough to begin to have an impact on its own planet in a way that creates and maintains an environment amenable to life. They call this the Gaian bottleneck.

The blue area at the bottom of the diagram shows the range of planetary environments that can form, while the yellow cylinder shows the conditions required for the formation of an “abiogenesis habitable zone (ABZ).” If a planet’s initial environment is within this zone, life can begin to evolve. As life evolves (green area) it creates wider zones of habitability, which allow for other life to evolve in turn.

To understand how this particular filter would function, consider the fates of Earth, Venus, and Mars. We now have strong evidence that Mars was once a warmer and wetter place than it is today, with many of the base conditions believed to favor the evolution of life. There’s less information available on Venus’ early history, but what data we do have suggests that it, too, may have once had liquid oceans and even a short-lived magnetic field. (Mars has remnants of such a field today).

The difference between our three planets is that both Venus and Mars may have lost the conditions that made them initially habitable more quickly than life on those planets could evolve to keep them habitable. From the paper:

Liquid water is not easy to maintain on a planetary surface. The initial inventory and the timescale with which water is lost to space due to a runaway greenhouse, or frozen due to ice-albedo positive feedback, are poorly quantified, but plausible estimates of future trajectories have been made. On Earth, dissociation of water vapor by UV radiation in the upper atmosphere is ongoing and will eventually (1–2 billion years from now) lead to the loss of water from the bioshell and the subsequent extinction of life on Earth.

Without life, liquid water may be quickly lost

The authors’ argue that early life may perform a vital regulating function on an early planetary environment by impacting both the planet’s albedo (how much light it reflects from the sun) and the greenhouse gases present in its atmosphere. They modeled how quickly a planet lost its water based on either a runaway greenhouse effect (Venus) or runaway glaciation (Mars). In both cases, the amount of water remaining on the planet is a fraction of its total by roughly one billion years old.

The Gaian bottleneck theory offers a new model for how life might be distributed within the universe, as shown below:

In an emergent bottleneck scenario, the conditions for life are rare, but once life evolves, it persists for billions of years. This assumption helps create the Fermi Paradox, because if even a handful of civilizations exist, we should have seen some evidence of them already.

If there is no emergence bottleneck, life should already be plentiful — think of this as the Star Trek / Star Wars hypothesis, where hundreds of species exist across the entire galaxy.

The Gaian model predicts an initial surge of life within the first billion years of planetary development, but that the vast majority of this life never survives long enough to advance beyond single-cell organisms. It predicts that the majority of life we’ll find out among the stars will be fossilized remnants of primitive creatures, assuming any evidence exists to be found at all.

Obviously we won’t be able to prove or disprove any of these models until we can actually evaluate the conditions around other planets. But if the Gaian bottleneck theory is accurate, we might find evidence for it on the moons and rocky planets of our own solar system. It’s virtually impossible to build a probe that can survive on the surface of Venus for any length of time, but Titan, Mars, Europa, and Ganymede might contain such life — or fossilized evidence of its original existence.

Tagged In

Another really silly theory. Fake rules and just nonsense. Why the heck everywhere else other than on Earth life should be dead already or die in a short time?
This is just another nonsense theory that resembles the Earth is flat and Sun is orbiting Earth crap of the past.

Joel Hruska

“Why the heck everywhere else other than on Earth life should be dead already or die in a short time? ”

It’s *almost* as if you could’ve read the article — or the paper, if you want even more detail — and answered those questions!

When you leave a comment like this, criticizing an issue that the authors’ thoroughly address (even if you don’t find my explanation substantial enough), you just make yourself look stupid.

The argument is that *biological* functions shaped the very early Earth in ways that allowed it to retain the initial characteristics that made it habitable. This was only possible because the Earth was initially friendly enough to microbial life that it was able to establish itself in sufficient density to create the necessary changes in the first place. On Mars and Venus, the initial colonies of life that arose following planetary formation may not have been well-established enough or simply not capable of counteracting the forces that eventually left both of these planets uninhabitable.

Given that we know single-cell life can have drastic impacts on the conditions of the Earth and the kind of life it can support, this is not some radical idea. The Great Oxygen Catastrophe fundamentally altered Earth’s entire biosphere some 2.3 billion years ago, and that was triggered by by cyanobacteria.

The authors do not claim the Earth is special, or unique — only that the specific conditions that allow life to continue existing on a planet past ~1B years may be rare.

Joseph Taylor

He does have something of a point. This paper is philosophy masking as science. Nothing they are saying could be proven or disproven without a million + years of observable data, faster than light travel or being contacted by aliens. So what really is that point?

Lorfa

The point is to examine various models that pertain to the Fermi paradox. By using what we know about physics, chemistry, and life on Earth we can attempt to understand how life is likely to form in the universe we live, where we might find it, and how we got here.

Einstein discovered that the universe was expanding before it was ever observed, he didn’t believe it but that’s not the point. The Higgs boson was hypothesized long before it was observed as well. When we sit down and work through the logic of various models we can discover a great deal. Observation is important in science of course, but it isn’t everything. We have to have models to make sense of our observations, and models that make predictions about potential future observations which tell us where to look and what to expect. That’s how we make progress, and that’s the “point”.

chojin999

Observation is everything.
Einstein discovered that the universe was expanding ?
The myth that everything that Einstein ever said always had to be the truth is silly and naive. Einstein had just his own theories. Whatever complex math he used to claim some proof of it actually doesn’t mean anything and it isn’t proof of a damn thing.
So you really think that it is good science be stuck on a tiny point that is this planet Earth of what highly likely is a limitless space and claim to know everything about it and what is going on everywhere out there with no direct proof ?
Sorry but that is not science. That is just fairy tales, fake theories, assumptions based on wishes.
And about the Higgs boson at CERN… it could be something else and something more that the military agenda behind all the accelerators built so far and the new ones is really interested in.

some dude

Big o wrong, theory actually help a lot, the reason is simple in this world there’s unlimited thing to observe but we have limited resource and technology, so theory will be used as a base so we know what to test and observe. Some of Einstein theory also got proven after we have technology to test it, this wont happen if they test random thing with hope to hit something without knowing what it is.

chojin999

So any fairy tale claimed to be “official science theory” is the truth and surely there will be some proof of it sooner or later? Yeah..sure… Please.

Opinionated Cat Lover

No, you just don’t know how to Science. That’s all.

Science is constantly refining and updating its ideas, and yes, sometimes it gets it wrong. But science is about producing ideas, studying the world to see if those ideas match the observations, refining them if they don’t, and taking all of those observations to produce yet more ideas.

What you’re asking for is blind faith. And then you get bent out of shape when we tell you ‘no’. :)

chojin999

There is a big difference between some fairy tales theories claimed to be “the official Science” and what real Science should really be.
People like you sound like the so called official Science fans of the past. The same for which the Sun was orbiting Earth and whoever questioned that had to be killed.

Opinionated Cat Lover

False Equivalency is False.

greybirdtoo

You _really_ don’t understand science. Your “fairy tale theories” statement proves it. Theories are beginning processes that then examine whether those theories are true or not, or even partially true. This leads to further examination. This theory is the beginning of that examination, and the article makes that clear, and that further examination will potentially show whether the theory pans out or not. You really should read more carefully.

grindovermatter

You think that the Rosetta comet is a disguised alien spacecraft. You are really in no position to criticize the scientific method.

Neutrino .

I though Hubble observed that the universe was expanding before Einstein explained why.

Opinionated Cat Lover

The only point he has is the one on top of his head. Science has addressed things we could not immediately observe time and time again. After all, how long was it between the theorizing of the Higgs Boson and its first detection? As for millions or more years of observation, while sometimes science takes the long path, I don’t think we’ll have to wait until long after we’re non-human to make observations about this hypothesis.

Science is about making ideas that fit observations, making additional observations to confirm or deny those ideas, and further refining the ideas. We have observed a lack of obvious signs of interstellar societies across the universe. We think that we should see signs of them. So someone came up with a hypothesis as to why we don’t (three actually), and posted them, and Joel came and wrote an article based on that hypothesis. Now we’re debating, and some of us (obviously, not Chojin) are coming up with alternate ideas…

That’s what the point is.

Joseph Taylor

There is a difference between a theory not being immediately observable and requiring exotic and potentially impossible technology like time travel, or faster than light travel to test it. This will never be anything more than a theory as to test it would require an observable sample size of known planets with life at various points in evolutionary development and the time scales of evolution to ever be proven wrong. This is not science its philosophy. If you enjoy that sort of thing, good for you. Unless we find life on europa, mars or are visited by aliens this course of investigation will be nothing ever more than idle speculation due to the size of the universe.

Opinionated Cat Lover

You honestly think that FTL and time travel are required to detect life on an alien planet? Broaden your horizons a bit. All we need is a powerful enough space-based telescope to see if an exoplanet has an oxygen atmosphere. And we only require a regular old STL, and WAY STL spacecraft to flit on over to Europa and see what’s under the ice. If we find life there, we just justified astrobiology right there and then.

And to answer my little rhetorical question, the Higgs Boson went 49 years between theorizing and discovery. I’m pretty sure that in 1965, people were saying ‘What’s the point? We can’t ever get sufficient power to make one of these things, so it probably doesn’t exist!’ Fortunately, other people, who understood what science is about, didn’t listen to them, and they managed to get enough power to actually cause one to form, a couple of years ago.

Techutante

Chojin999 is a forum troll of limited intelligence, so don’t worry about him.

But regarding detecting life, any signal (Or visual detail we can observe) that we can see has been underway for a minimum 2.5 million years already for it to have reached us. Given that we’ve only been a wireless communication society for about 100 years, and could wipe ourselves out within another 100, what are the odds we would detect someone else’s 200 year radio signal window before they annihilated themselves, out of all the possible signals from space we could be getting. AND, even if we did detect it, the odds of a society lasting 2.5 million years+ are pretty low, so it would just be an echo of a lost civilization.

I guess that is why they call them theories because there is no way to prove things with absolute certainty without being able to observe it in person.

chojin999

Insulting me like that just shows a lack of professionalism.
The whole argument you base everything on is not sound.
You can get angry and whine like a little kid as much as you want but if you start insulting people like me that point that out you surely don’t look like an adult.
How can you even remotely believe in such fairy tales to the point that you start insulting readers of your articles here that dare to point out that theories like that are just plain silly and narrow minded?
Why would this planet Earth where we humans live right here right now be so special and all other many billions of planets out there be so unlucky so that everyone there would just die?
It doesn’t make any damn sense. It just can’t be true. It surely isn’t true. Even remotely thinking that everything out there is dead and life can’t survive while Earth would be magic is beyond dumb. These theories are dumb. Just like the theories of a flat Earth and the Sun orbiting Earth were.
And some bacteria, fungi or other nonsense explanation they give with these silly theories is just more fairy tales not based on real proof of any kind.

Opinionated Cat Lover

A good explanation would be wasted on you. That is an insult. What Joel said to you is a simple statement of fact — the answers you seek are in the article you are commenting on.

chojin999

You think to be smarter than anyone else. Go on with your arrogance and narrow minded approach thinking to know the absolute truth and the official science is always right and true.

Opinionated Cat Lover

No, I only think I’m smarter than you. Learn the difference. ;)

chojin999

You aren’t smarter. You made up you own theory to claim to be smarter. And you think that that is science too.

Chojin says scientists are making claims without any evidence.
Chojin continuously makes claims without any evidence.

Chojin is a real treat.

chojin999

You are a threat and a stalker.
You pop up out of nowhere following me and you start insulting. I wonder if other accounts here of people attacking and insulting is again just you. Whoever you are you keep creating fake accounts. You are criminal.

grindovermatter

Nah, I’m just a big fan of your work. <3

grindovermatter

“Why would this planet Earth where we humans live right here right now be so special and all other many billions of planets out there be so unlucky so that everyone there would just die?”

Damn, Aredo. I hope you brought some croutons for that word salad!

chojin999

You keep writing the “aredo” crap. You are obsessed with nicknames on the ‘net you keep stalking. Only a psycho would do that. Along with creating multiple fake accounts to vote your posts up and make you look right.. so you think in your clearly disturbed mind.

grindovermatter

You’re like that kid on the playground who throws rocks at the other kids and then complains that no one likes him.

XenoSilvano

A single discrepancy is all that is required to render an equation completely invalid.

Due it’s own current state of inadequacy, the scientific method can only help us so much in extrapolating observable phenomena.

maurits

The answer to your question is easy. The article doesn’t claim that life on earth is special. It tries to argue, based on the best scientific knowledge we have, how we can understand that up to now we haven’t found any life on other planets. The reasoning points out that life may have originated and even evolved on many planets. Don’t forget that over 99% of all species on Earth are extinct, so extinction is the rule.You could also wonder what is so special about the currently living species that they are alive and nothing else. The answer is just that, they are alive Question. why do you think calling something dumb isn’t insulting?

Lorfa

Joel, I warned you before about Chojin the troll! Don’t let him trick you into feeding him!

chojin999

How childish you are with your nonsense use of the “troll” word. Maybe you even think to look cool.
So what do you think to accomplish like that? Scare me?
Force me to shut up? Force me to say only what pleases you and never dare to question anything?
Grow up!

Opinionated Cat Lover

Look up the definition of the world “troll”. You actually fit that definition very well. The article is about why we don’t see evidence of alien life all across the cosmos given that we’re pretty young (10,000 years of ‘history’, on a world that is 4.5 billion years old, in a galaxy that is 13.2 billion years old (we think), in a universe that is at least 13.7 billion years old. You’ve chosen to come here and scream about the post, asking nonsense questions that you could have answered yourself, and made your post better, had you just read the article. Sure, you’re staying on topic, but your comments are extraneous and inflammatory, and your refusal to do simple reading shows you’re not here for rational discourse. That, chojin, is the definition of troll.

Don’t want to be labelled a troll? Stop with the behavior that gets you labelled as a troll. And you can do that while questioning things, too. ;)

chojin999

Grow up!
I don’t care about a bunch of delusional kids “labelling” me or anyone else “a troll” on the ‘net.
You think to be so smart and better than other people and you keep insulting and whining and using silly childish words like the “troll” thing thinking that it is so fancy and cool and that would make you look like a very smart guy… in your wet dreams.
It is just plain pathetic. You are beyond childish and silly.
No one cares about a bunch of rude kids writing nonsense on the ‘net and insulting other people. You scare no one.

Opinionated Cat Lover

That was funny. Tell me more. :)

You shouldn’t be scared, trolikins. You should be ashamed of yourself. But you’re not. So I’m just going to mock you some more. Welcome to the internet. :)

chojin999

You are a shame to the human kind going on the ‘net insulting people and attacking thinking to look cool that way.
You don’t look smart, you don’t look cool. And whatever you say has no power on anyone.

Opinionated Cat Lover

I have the power to make you scream vitriol all over this site 4 times. :)

And as for looking cool? You wouldn’t know cool if it bit you on the rear. Kook, on the other hand….

XenoSilvano

who is being the troll now

Opinionated Cat Lover

Sorry, I don’t play nice with people who call people they disagree with being childish. If you define that as trolling? Well, I do enjoy trolling trolls. :)

grindovermatter

“No one cares about a bunch of rude kids writing nonsense on the ‘net and insulting other people.”

Then why do you perpetuate it?

Mongoose Snakeater

Poor troll with hurt feelings. The world is big and scary, little guy, but you’ll do fine.

chojin999

You really write like a very little whining kid.

Opinionated Cat Lover

Oh, the “I know you are but what am I?” gambit. And you say he writes like a whining kid. That is rich.

chojin999

grindovermatter you are so pathetic. Even a little kid would figure your lame tactics out. Creating multiple fake accounts and writing the same nonsense over and over is not going to make you look smart.

Opinionated Cat Lover

They say that it can’t be paranoia if the world is out to get you, but in this case, it’s just paranoia. Which is sad, because all of this is because you can’t take criticism.

grindovermatter

I like how you just admitted that you’re not as smart as a little kid, because you haven’t figured out jack. :)

grindovermatter

And you write like someone who doesn’t understand basic sentence structure.

chojin999

“grindovermatter” you are using multiple fake accounts here. Anyone can see that. You keep writing the same thing and attacking me the same way. And you are even so psycho to vote yourself up between all your fake accounts.
You seriously think no one would notice that? Oh, yes.. you are so powerful, so smart… no one can figure it out. You are a genius, right?

Opinionated Cat Lover

Must be sleep posting again. :P Dude, you’re not even a quarter as smart as you think you are. ;)

grindovermatter

Wrong as always, Aredo. But hey, whatever strokes your ego.

Richard “Raptorian” C.

I sorta feel bad for you.
No one agrees with you, and they won’t agree without evidence.
Do you ever give up?

Mongoose Snakeater

Thanks for continuing to produce great content, Joel.

BillBasham

The analysis is cool and interesting, but it seems only applicable to a very small range of definitions of ‘life’.

It’s a bit hard to believe that there won’t be some form of life that evolves inside of some stars. The energy budget is high and presumably there are some long term selection pressures that will shape ‘survivors’ – certainly there is a fair amount of random generation to provide a pool to select from.

Most of that also applies to our internet – we may have already created aliens…

Joel Hruska

Bill,

Not really. The theory can be extended to very different kinds of life, because the argument remains the same. The argument is that a rocky planet may only be habitable to the species that appear on it for a relatively small amount of time *unless* those species begin to exert pressure on the environment that results in the planet remaining habitable.

You can swap in whatever forms of bizarro biochemistry you prefer. Silicon-based life. Uranium-based life.

The sun is unlikely to contain life because it’s far too energetic. Biological structures can’t form — they immediately vaporize. Because there’s no known way for complex molecules to form, there’s no known way for a star to sustain life. Since no one has ever argued that molecular iron suspended in a plasma state would qualify as a life form, it’s very hard to envision a type of species that could exist within a star.

Neutrino .

Since we don’t currently have the slightest clue what conciousness is (beyond some vague ’emergent pattern’ handwaving), it isn’t necessarily the case that conciousness even requires anything that we would recognise as a biological component.

Riely Rumfort

>_>
I know better, but there is little point in telling those whom don’t.
They’re more realistic to me than you are Joel.
We’ve never had a physical conversation.

Joel Hruska

What or who are you replying to?

Riely Rumfort

My best guess, Pleiadians, in one of these(link).
A craft driven by plasma density in an XYZ axis coordinate system. If you’ve seen the movie ‘Explorers’ it’d give you an idea of the style by which it moved. Basically it can triangulate gravity and either pull/push/stabilize itself relatively.
It came down to about the height seen in the photo from being a dot of satellite elevation, had a telepathic chat, then following, in less than a second returned to this elevation, followed by a final maneuver in which it shifted away completely, also rapidly. https://s-media-cache-ak0.pinimg.com/736x/f2/60/e5/f260e55bc3abdf1e23fcb20e4d028a48.jpg

Plyphon

Drugs, I think

JD Rahman

We have an additional problem which is not usually addressed because we know so little about it.

Dark Matter. So the theory is the Universe is ~4% Matter, ~23% Dark Matter and the remaining ~70% Dark Energy. So we cannot observe or interact with over 95% of the universe.

Since there is so much more Dark Matter, there’s probably more systems composed of Dark Matter.
And perhaps Dark Matter based life?
Some of which may be intelligent and technologically advanced?
And since there’s more of them, the window of opportunity to observer/interact may be higher?

They’re probably doing flybys just outside our Solar System but we can’t see them.

Lorfa

It’s not clear that dark chemistry is possible to enable ‘dark life’. It does not interact with the EM force as we know. It might interact with itself, but as far as we can tell this interaction would not be very strong.

Antoni L.

Dark matter only interacts through gravity as far as we know, so unless there’s a fifth unknown force (other than the electromagnetic, weak and strong nuclear forces, and gravity), I don’t think dark matter can interact with itself in such a way as to form complex forms that we can call life.

chojin999

No one knows what dark matter looks like and what is there. And why life shouldn’t exist in dark matter if it’s real?

stephan schwebke

A couple bottlenecks they leave out: life, if given time, will evolve past the microbial stage, and life tends toward a bigger is better philosophy, but will that life increase in physical size, like the dinosaurs, or cranial size, like the homos, sapiens and otherwise; also, having leaned toward a larger cranial size, will that planet survive the idiocy of an emerging species, as this planet is struggling to do. We have had two crises, in the last 50 years, either one of which could be a planet destroyer: nuclear war and global warming. How many more lay down the road, and how may more excuses does a species need to perish?

Lonnie Veal

Or another way of putting it: “Why isn’t the Sky filled with Ships?”

I say, let’s count our blessings. Maybe, it’s most likely that Space Travel, much less Interstellar Travel is a highly advanced endeavor with a lot of logistical and technological barriers to be overcome…and not every civilization can reach that point to start jaunting freely from star to star—assuming FTL is even possible.

On the other hand, Hollywood Space Invader movies aside…I’d much rather we’d let some years and some more Technological progress happen before we meet with another Alien race in Neutral Space, We really don’t want to wake up and find a Technically Superior Race sitting in Orbit and looking down on us…

…Because then, we wouldn’t be Humans…we would be ‘The Natives’

http://panduanpc.com doge

If we count earth-like condition to make it happen, yes.

Who knows if life could established in those gaseous and oceanic planets that based on ammonia or methane instead of water as life basic resource. Life happen on earth because God (or lucky random chemical reaction hit) happen which later start a life form.

Those planets condition looks extreme just from our point of view.

Matt Perdeck

Although I’m convinced there are many alien civilizations out there, I’m totally unsurprised that we haven’t made contact yet.

The chances of intelligent life developing on a given planet seems very low. For example, lots of species on Earth have evolved great eyes or great claws, but we are the only ones to have evolved the intelligence (and dexterity in our limbs) to create some serious space traveling technology. Intelligence, and the big energy consuming brain it requires, doesn’t seem a real advantage for most species.

This means that the nearest alien civilization is probably far away. Say 1000 light years – which is not far in terms of our galaxy.

We have been sending radio signals for less than 200 years. So that nearest civilization hasn’t received those yet. If there are lots of them and they’re all zipping around in faster than light space ships, they might have stumbled upon us, but that is a big if.

If the nearest civilization has had radio and tv for over 1000 years (likely), we might be receiving their signals today. But how do you distinguish an alien I Love Lucie in an alien language sent using alien formats from background noise?

Opinionated Cat Lover

And we’re getting more and more quiet in our transmissions. Give us another hundred years, and we may emit no radio-wave length transmissions.

However, that’s not the only way you can see an alien society. In 100 years, if science continues to evolve at the increasing rate it is today, we may be barely human, with the first bits of work done on a megastructure that will be visible for thousands of light years. Give us a million years, and our entire solar system should be a massive fusion reactor powering a society that will take that massive amount of energy and achieve things we couldn’t even dream of today. Give us a billion years, and we would have spread across the known galaxy, and built similar Dyson shells around most stars in the galaxy. That should be visible from across the universe. That no one has seen a galaxy with that sort of signature makes us wonder: “Why?” Hence these sort of articles.

On the other hand, we have no idea what a real Dyson shell looks like. Maybe ‘Dark Matter’ is actually a collection of Dyson Shells that absorb all energy. That would be a mind-bender. And the aliens snicker from the star 10LY away that is filled with advanced life, at the silly humans who think they are so advanced. :D

VirtualMark

Interesting, but it ignores some of the other reasons that we haven’t detected alien life. Such as the differences in technology – we’re very unlikely to ever have a Star Trek type scenario, with lots of races at roughly equal levels of technology. Mainly due to the huge lifespans of planets, and the relatively short time it takes to progress scientifically and technologically.

The Earth is roughly 4.5 billion years old. Even if we discovered an identical twin Earth that happens to be 4.6 billion years old, assuming that life had followed the same path, they’d be 100 million years ahead of us in technology. Even 100 years is a long time in technology, we can’t even begin to comprehend 100 million years of advancements.

And how could we detect a civilization that’s 100 million years more advanced that us? Who knows. We’d probably be like insects to them, and if they don’t want us to find them, we won’t.

Rawr

My theory is they’re avoiding us like the plague seeing how barbaric we still are as a species. If we ever do encounter alien life, I’m definitely telling them to avoid us like the plague but that’s just me. I know more harm we could do to them in the long run if they let us tag along. Heck we still need imaginary lines to live among one another.

exomike

There are plenty of sentient aliens. They are sentient enough that they avoid us out of disgust.

Riely Rumfort

I actually think much of it has to do with not modifying the course of a civilization(which I’m not sure we’re all that civil), much like the law at the start of Star Trek; Into Darkness.

exomike

A nicer explanation from a much less cynical gentleman.

Yes,the Prime Directive prohibits Starfleet personnel from interfering with the internal development of alien civilizations.

We however need to be pulled over by the sanity police and given citations for the careless greed induced damage to the life support systems of Spaceship Earth. Spaceship Earth’s life support systems are no longer up to code and on the verge of catastrophic failure.

A real Planetship Captain and crew will be sent aboard to set about saving Spaceship Earth until the earthlings can be properly educated to handle their own planet. Like all ship Captains he will have complete power to assure the safety of the ship and all it’s occupants…, no matter the waling and moaning and gnashing of expensive dentistry

This is after all to only way to go even without helpful aliens. Otherwise it’s like Country Joe said, “Whoopee, we’re all gonna die!

There are the outliers among us of both extremes, destructive and consciously creative, but just like a non-mutualistic virus to our host I think we’re being given the choice to radically shift or diminish. Appears to me the greater whole of mankind has chose to keep it’s course towards the cliff, so a culling it is. Ready or not the precipice approaches in the next decade and as Voltaire stated, Luck favors the prepared. To me it comes down to foresight being the primary driver of survival of the fittest. The same way looking both ways saves you in youth from cars the same can in adulthood be said of looking to both future and past occurrences for answers of what’s forthcoming. Today’s answers used for tomorrow’s problems based on past events as precursors will be the next ‘fittest’. Plenty of wisdom and innocence may burn out in the process but such is life.

Glenn

It is an interesting theory. But I would like to know how specifically biology stabilizes the atmosphere. I would think that during the Ice Age we would have ended it all there.

Opinionated Cat Lover

The Ice Age really wasn’t that extensive. We didn’t come anywhere near a Snowball Earth in the past 250,000 years.

We did come close at one point. The biosphere actually managed to over-stabilize the atmosphere and create a situation where the Earth froze, possibly all the way to the equator. The notion is that we got lucky — Earth managed to pull out of the ice-box, and life exploded once that process finished. Delay the onset of warming conditions a few years, or extend the ice coverage more, or cool the planet’s inner layers a bit more, and Earth may have never came out of the freeze. Conversely, heat things up a bit more, and Earth’s oceans boil off, life stops, Carbon sinks are forced into the atmosphere, and boom, Venus.

Biology and Geology have helped to keep Earth habitable. The question is, why us, and could that process have short circuited on many other planets and we just got lucky?

Hansjurg

We’ve been reporting the same kinds of UFOs since we first became self-aware.

And before you ignorantly yammer about the great distances between stars please Google “time dilation” and “Bussard Ram Jet.”

Menno van der Coelen

It might just be that we expect to much. For instance intelligence does not necessarily lead to technological advancement. Neanderthals for instance where making the same stone tools for 1000s of years and where eventually outperformed by us and our superior technology.
As for our detectability as life on earth we are only actively sending out signals for a little over a hundred years. This means that our radio signals are still undetectable in most of the milky way let alone the universe.
The other end will have the same problems. Even if another civilization at the other end of the galaxy is 10.000 years ahead of us technologically we’d still be waiting for 1000s of years before their first radio signal reaches us. (if it wasn’t too dissipated to hear over the background noise by that time).
These distances also prohibit easy empire building across a galaxy. There is little incentive to head out to the stars. I mean the furthest we’ve gotten is to the moon. And that was decades ago. Unless we have an active incentive to leave our solar system or superior engines which would cut travel times significantly. we just won’t leave.
And I think in crash course astronomy they said that that our type of star is one of the first of a wave of sun-like stars. We might just be one of the first.
We also don’t know how long we shall be detectable. Maybe tomorrow someone has a new revolutionary idea that will end radio as a means of communications. (I doubt it will be tomorrow but it could happen).
I think there are enough unknown factors to assume intelligent life out there even if we don’t see any evidence (yet). besides we haven’t been looking all that long.

Vaidas Sukauskas

I suggest you read a book by John Gribbin, “Alone in the universe”. it gives plethora of reasons of why we didn’t encounter aliens yet. Gaian filter is just one of dozen such filters. The whole concept is called ‘great filter’ or ‘Rare Earth hypothesis”

jimv1983

This is all based on the assumption that if the galaxy did have other life that we would know about it. There are several explanations why we haven’t found evidence yet.

Maybe we haven’t been looking long enough. The galaxy is a HUGE place and we’ve only looked at a tiny fraction of it.

Maybe there are alien civilizations out there that have discovered us but consider us so primitive that they don’t even bother talking to us. How many people stop and talk to ants? Maybe any aliens that have discovered us see us the same way.

Maybe there are lots of alien communications around us but our technology is so primitive we don’t even know how to detect those transmissions.

Maybe we really are the only life in the galaxy or maybe up until now any planet in the galaxy wasn’t habitable for life. Maybe we are the first.

darkich

What is puzzling to me is, why does the scientific community think we should have seen the “evidence” by now?!?

Let me ask in return, and hopefully someone knowledgeable enough can answer – if we assume that there are 1000 technologically advanced civilizations in this galaxy, and spread them out evenly across that space.. Would any of them detect the radio waves from Earth by now?

FrankenPC .

If we’re talking pure philosophy here, what if the universal model of baryon asymmetry also applies to life? Maybe WE are the freak occurrence? Another one is, what if dark matter/energy is a slightly out of phase physics system that still complies with gravity but actually houses the real universe? And it’s teaming with life? To ‘them’, we are the dark matter and energy that they just can’t figure out.

Tó

My Ocham’s Razor on this matter: I believe there’s plenty of life in the universe. But it’s all so far from one another that it’s simply Physically impossibly (or extremely improbable) for any two civilizations to perceive each other in their lifetimes…

http://www.funstufftosee.com/ Dozerman

Or:

“There is no (relatively) practical way to produce a warp drove/travel faster than light” + “The universe is ridiculously huge” + “civilizations will trend towards the most efficient means of transmitting energy possible, making the windows to pick up their signatures very very small” = “where is everybody?”

Sam al

There are 400 billion galaxies in the universe…each containing billions of stars and hundreds of light years away from each other. Imagine this. You live in New York and are alone…and you want to find out if there are other humans that exist. If you compare it to the universe….you might just be the unlucky one and all alone on your continent…yet there could be a dozen people in australia. But if we exist, then the rule is broken and others can exist too. Read the Fermi Paradox.

ExtremeTech Newsletter

Subscribe Today to get the latest ExtremeTech news delivered right to your inbox.

Use of this site is governed by our Terms of Use and Privacy Policy. Copyright 1996-2016 Ziff Davis, LLC.PCMag Digital Group All Rights Reserved. ExtremeTech is a registered trademark of Ziff Davis, LLC. Reproduction in whole or in part in any form or medium without express written permission of Ziff Davis, LLC. is prohibited.